implementing Refresh Token Rotation in ASP.NET Core Identity System
This might be a silly question, but I'm currently implementing an authentication system in my ASP.NET Core 6 application using the Identity framework. I've set up both access tokens and refresh tokens for handling user sessions. However, I'm having trouble implementing refresh token rotation. When making a request to refresh the token, the application sometimes returns a `401 Unauthorized` behavior, and I need to seem to track down the root cause. I have configured my `Startup.cs` to use JWT Bearer authentication, and I'm using the following code to generate the refresh token: ```csharp public async Task<string> GenerateRefreshToken(string userId) { var refreshToken = Guid.NewGuid().ToString(); var tokenExpiration = DateTime.UtcNow.AddDays(30); // Save refresh token to database (not shown) return refreshToken; } ``` When I send a request to refresh the token with the following code: ```csharp [HttpPost] [Route("/refresh")] public async Task<IActionResult> RefreshToken([FromBody] RefreshTokenRequest request) { var user = await _userManager.FindByIdAsync(request.UserId); if (user == null) return Unauthorized(); var savedRefreshToken = await _context.RefreshTokens .FirstOrDefaultAsync(x => x.Token == request.RefreshToken && x.UserId == request.UserId); if (savedRefreshToken == null) return Unauthorized(); // Validate token expiration and rotation here (not shown) // Generate new tokens (not shown) } ``` I perform database checks to ensure the refresh token exists and belongs to the user, but I'm not sure how to correctly handle the situation when the refresh token is expired or has already been used. I also notice that after a refresh, if I try to refresh again with the same token, I always get `401 Unauthorized` which is expected, but it seems inconsistent when I actually rotate the token. I've tried logging the flow and checking the token expiration, but sometimes it seems like the refresh is valid, yet I still receive the unauthorized behavior. What am I missing? Is there a specific best practice for handling refresh token rotation that I should be aware of? Any insights would be greatly appreciated! Any help would be greatly appreciated!